def openFile (filename):
        """Given a filename, read the contents of that file.
        """
        f = open(filename)
        line = ''
        a = []

        while 1==1:
                line = f.readline()
                if line != '':
                        if line != '\n':
                                a.append(line.rstrip('\n'))
                else:
                        break
        f.close()
        return a

if __name__ == "__main__":
	allTix = []
	allTix = set(openFile("all.txt"))
	touchedTix = []
	touchedTix = set(openFile("touched.txt"))
	notTouchedTix = allTix.difference(touchedTix)
	print notTouchedTix
